I did adding the class or process to 'GDI Capture List', but the Ranorex still did not get all Cell in Grid. It got cells in the first row and first column as RawText and other white cells as RawTextBlock.

With my grid, I have similar problems which I solved as follows:
Find the x coordinates of your column and the y coordinates of your row. Then, you can click in your cell.
You can find the coordinates as properties in the RawText